By way of example, French Patent No. 2 571 461 describes one arrangement of torsion damping device of the kind commonly referred to as a double damped flywheel. Circumferentially acting coil springs are arranged between the two rotatable parts so as to be compressed when the angular displacements take place. The two rotatable parts comprise a power input part, normally driven, for example from the vehicle engine, and comprising essentially two parallel annular wheel members which are secured together radially outwardly thereof by a heavy spacer ring. The other of the said rotatable parts is a power output part, driven by the power input part and including at least one radial plate which is arranged to rotate in its own plane between the two wheel members of the power input part. Each spring is mounted between two thrust members made of a rigid plastics material, these thrust members being pivoted in rounded notches formed in the wheel members of the power input part. Two of such thrust members thus lie facing each other in the space defined by two through openings formed respectively in the two wheel members, with a spring being mounted between these thrust members. The thrust members have cavities formed in their end surfaces facing away from the spring; and fingers, extending substantially circumferentially and formed in the radial plate or plates of the power output part, engage in the cavities formed in the thrust members.
Under the effect of centrifugal force, the springs make frictional contact with the inner surface of the spacer ring. This frictional contact is accentuated by virtue of the positioning of the springs at a relatively large radius from the axis of rotation, and also because of the action of the pivoting thrust members in allowing the springs to deform with increased amplitude. The inner surface of the spacer ring thus defines contact zones for the springs. It is found that deterioration occurs in these contact zones. This can take the form of any of the following, namely fretting, partial penetration or "coining" of the contact zones by the turns of the spring, and excessive wear in certain parts of the springs. The springs can thus be progressively weakened, resulting eventually in broken springs.